Fabric treatment



NOV. 4, 1969 f:- LORENZ ET AL 3,476,501

FABRIC TREATMENT Filed March 1'7. 196

H Ti WE.

OOOOOOOOOOOOO WATER United States Patent O 3,476,501 FABRIC TREATMENT Fritz Lorenz and Ernst Weiss, Wattwil, Switzerland, as-

signors to Heberlein Patent Corporation, New York, N.Y., a corporation of New York Filed Mar. 17, 1966, Ser. No. 535,087 Claims priority, application Switzerland, Apr. 26, 1965, 5,749/65 Int. Cl. D06m 1/10 U.S. Cl. 8-125 6 Claims ABSTRACT OF THE DISCLOSURE Disclosed is a process for preparing linen-like fabric comprising contacting a cellulosic fabric with a sodium hydroxide solution at 10 to 20 B. and below 0 C. and winding the fabric onto a drum and removing the sodium hydroxide solution by passing water radially from the interior of the drum through the fabric.

This invention relates to a process for treating fabric, and more particularly, it relates to a process for obtaining linen-like effects in cellulosic fabrics.

It is known to treat fine cotton fabics with alkali lye of mercerizing strength at temperatures below C. to obtain a transparent effect in the cloth. It is further known to subject coarser and thicker cotton fabrics, such as those made from yarns with a iineness not in excess of metric yarn number 135.5 to such lye treatment to obtain fabrics having a linen-like quality. fln commercial use, this treatment is carried out so that the wet goods are immersed into caustic soda of about 30 Baum (B.) for 1-2 minutes to impregnate them with the alkali.

While the foregoing process has been an important one for finishing fabrics, it has many disadvantages. One of the principal disadvantages is that a relatively long treatment with lye is required, so that a special machine having a long lye through is necessary if commercial production of fabric is to be obtained. The purchase of a special machine just for the purpose of carrying out this finishing process is expensive.

It is also possible to produce linen-like effects on cotton by immersing the dry fabric in caustic soda-solution of -20 B. at temperatures below 0 C. for a 10-30 second impregnation period, and then finishing the fabric in the usual way. By comparison with the first-mentioned process, it is possible to carry out this treatment on a conventional mercerizing machine and the purchase of a special machine is thereby eliminated. Nevertheless, such a process can be carried out only at installations where mercerizing equipment is available.

Moreover, in addition to the capital investment and floor space required for a mercerizing machine, great quantities of hot water are needed adequately to wash the lye out of the material. Not only do the water and utilities required to heat it result in high operating costs, but there is a considerable quantity of dilute alkali which must be disposed of. In the past it has also been preferred to utilize quantities of acids to neutralize all excess alkalinity. Such acid treatment not only increases the chemical cost of preparing the material, but it adds an additional complication to the process and introduces further waste dis- 4 posal problems.

This invention provides an economical method for producing linen-like finishes on cellulosic textiles and obviates the use of large quantities of water, the use of diluted acids and large capital investment or special machinery. Also in the new process, the recuperation of the caustic soda lye is much more economical, because the primary lye issuing from the lye eliminating process is "ice much more concentrated than when eliminating the lye on a conventional mercerizing machine.

Briefly, the process of this invention involves contacting a cellulosic fabric with a sodium hydroxide solution at temperatures below 0 C. so that the fabric is impregnated with the solution, winding the hydroxide-treated fabric circumferentially into a perforate drum or cylinder, maintaining the fabric on the drum and subsequently removing the hydroxide from the fabric by passing water radially from the drum through the fabric. Thus, the process of this invention provides a simple and economical method for the production of linen-like and similar opaque stifening effects on fabrics containin-g cellulosic fiber material.

Attempts have been made to cool the textile fabric after impregnation with the lye at room temperature but these do not produce the highly desirable linen finish. IIt has surprisingly been found that these excellent linen effects can only be produced by observing the sequence of steps as set forth herein. Thus, the desired effect is obtained only if the fabric is impregnated with the cool lye and then wound onto the drum and held in this condition.

There has thus been outlined rather broadly the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention which will be described hereinafter and will form the subject of the claims appended hereto. Those skilled in the art will appreciate that the conception upon which this disclosure is based can readily be utilized as a basis for the practice of other modes of the invention. It is therefore important that the claims be regarded as including such equivalent construction and features as do not depart from the spirit and scope of the invention.

A specific embodiment of the invention has been chosen for purposes of illustration and description, and is shown in the accompanying drawings which form a part of this specification wherein:

FIG. 1 is a lateral view, partly in cross-section, of an illustrative form of apparatus which can be utilized in the practice of this invention; and

FIG. 2 is a longitudinal cross-sectional view taken through the line 2-2 of FIG. 1.

As used herein, the term fabric refers to textile materials made by weaving, knitting, plaiting, and felting or otherwise manufacturing materials suitable for cloth, clothing and the like.

The term cellulosic fabric is understood to mean fabrics comprised of natural or regenerated cellulose. Especially suited for the practice of this invention are woven or knitted fabrics of natural cellulose such as cotton or of mixed spun yarns of natural cellulose and staple fibers of regenerated cellulose. Further, fabrics comprising the usual types of regenerated cellulose as well as highwet strength regenerated cellulose are also suited to the practice of this invention. The cellulosic fabrics can also contain quantities of synthetic fibers, preferably those not adversely affected by alkaline solutions. The process of this invention is applicable to undyed, predyed, and/or printed goods. It is also possible to practice this invention on bleached goods which may be dyed and/or printed after the treatment by the herein disclosed process.

The sodium hydroxide solutions used in the practice of this invention should have a strength on the order of from about 10 to about 20 B., and in some aspects of this invention the preferred concentration of the aqueous sodium hydroxide solution is from 13 to 18 B. It will be understood that equivalent alkaline materials, desirably alkali metal hydroxides, are also encompassed herein but that sodium hydroxide is the preferred alkaline material because of superior properties, reasonable cost, and ready availability. l

As set forth hereinabove, the sodium hydroxide solution should be at a temperature of below C. In the commercial practice of this invention, it is preferred that the lye be contacted with the fabric at temperatures of from about -5 to 10 C.

It has further been discovered that once the fabric has been impregnated with the sodium hydroxide solution at the requisite temperature, it can subsequently be handled at room temperature, since a temperature rise during its residence on the drum does not adversely affect the results.

After treatment with the sodium hydroxide solution, it is preferred to remove the excess solution, as for example, by draining or by compressing the fabric between rolls. The fabric is then wound in its open width onto a perforate drum or cylinder rotatable around its longitudinal axis. During winding of the material onto the drum, the latter is rotated at a relatively low speed according to the speed at which the fabric is delivered on the order of from about 20 to 40 r.p.m. The time needed for batching and handling the fabrics on the drum before washing out the caustic soda with hot water ranges from about 30 to about 90 minutes.

Thereafter hot water is forced radially from the nterior of the drum through the fabric to wash the alkali from the cellulosic material. A rather concentrated alkali solution is obtained during initial stages of the washing and this solution can be returned t0 the process after its strength has been augmented by recuperation or with additional alkali. The required radial movement of hot water through the fabric is obtained by rapidly rotating the perforate drum on its axis to create centrifugal forces for driving the water through the fabric in a radial direction. It is preferred to rotate the drum at speeds in the range of from about 5() to 400 r.p.m. for this purpose.

The drawings illustrate an embodiment of the invention as follows: The cellulosic fabric 11 is introduced into trough or vessel 13 closed at the top by means of cover 20. The exterior of the walls, the bottom, and cover 20 of trough 13 are covered with a layer 19 of heat insulating material. Rollers 12 are positioned at the lower and upper parts of the trough. Cover 20 is provided with oblique slots extending the widths of the rollers so that the textile fabric 11 to be treated can be fed into the trough, passed through the rollers in successive loops alternately from top to bottom and bottom to top in the interior of the trough and finally withdrawn from the vessel.

After leaving the trough 13, the fabric is passed through a pair of rollers 14;, 14' to remove excess solution. The fabric 11 is wound in its open width onto rotatably mounted drum 15. This drum has a diameter of approximately 50 mm. in one embodiment.

Referring to FIG. 2, drum 15 is provided with a perforate exterior and is mounted on a central perforate hollow shaft 16. At one end of the shaft a hollow spindle 17 is inserted, and this spindle is journaled in bearing 21. Spindle 17 acts as a conduit from a hot water feed line (not shown) to the interior of drum 15. At the opposite end of the shaft a solid spindle 18 is journaled in bearing 22. The drum is rotated by means of an electric motor through a drive shaft (not shown) which drives spindle 18.

In use, trough 13 is filled with caustic soda solution having a concentration of 20 B. which is maintained at a temperature below `0 C. The running speed of fabric 11 is preferably adjusted so that the cold caustic soda acts from about 10 to about 30 seconds upon the fabric. When the fabric moves through the nip of rollers 14, 14', the excess lye is squeezed out.

The fabric is then wound in its open width onto the drum which is rotating at 20-40 r.p.m. The winding can be conducted at room temperature, and the fabric is then handled in this condition. Thereafter, the fabric is washed free of the sodium hydroxide by means of hot water flowing through spindle 17 into hollow perforate shaft 16. The drum 15 is rotated at speeds of 50 to 300 r.p.m. and the Water is forced radially through the perforations in the hollow shaft 16 and drum 15 and into and through the textile fabric 11 to the exterior.

The invention will be further understood by reference to the following examples which illustrate embodiments of the invention.

EXAMPLE I A conventionally bleached cotton batiste having a count of 106/91 per inch and English yarn numbers 80/95 is passed through the apparatus described above at a fabric speed of 60 meters/ min. The fabric is thereby impregnated for 15 seconds with a sodium hydroxide solution of 170 B. at a temperature of 8 C.

After leaving the lye bath, the fabric is compressed between rollers 14, 14 and wound onto drum 15 at room temperature. At the beginning of the winding operation the drum rotates at 40 r.p.m. and the rotational speed is decreased as the diameter of the drum with the fabric wound thereon increases. The fabric is then handled on the drum so that the total winding and handling time is 75 minutes.

Thereafter the roll of fabric is rinsed free of sodium hydroxide by feeding hot water into the interior of the drum. In order to force the water radially through the fabric to the exterior, the drum is rapidly rotated -at speeds of 50-300 r.p.m. Washing with hot and cold water is continued until the neutral point is reached. The fabric is dried on a tenter frame and calendered. A slightly stiffened tine fabric having typical linen character is obtained.

EXAMPLE II A bleached cotton cretonne fabric having a count per inch of 45/ 45 and English yarn numbers 12/ 12 is passed through the apparatus shown in the drawings at a speed of 40 meters/min. The fabric is impregnated with a sodium hydroxide solution with a concentration of 16 B. an-d a temperature of -8 C. for 23 seconds. The fabric is passed through the squeeze rolls and wound onto the drum at room temperature for a total winding and handling time of 45 minutes.

The fabric is then washed free of sodium hydroxide with hot and cold water as set forth in Example I. Subsequently the fabric is dried on a tenter frame and calenidered under high pressure.

A wash-proof stiifened fabric with typical linen-like hand and appearance is obtained.

EXAMPLE III A bleached and dye'd cotton Calico fabric having a count per inch of 72/ 64 and English numbers 40/40 is passed through the apparatus as shown in the drawings at a speed of 60 meters/min. to impregnate the material for 15 seconds with 18 B. sodium hydroxide at 9 C. The fabric is passed through the squeeze rolls and wound onto the drum at room temperature so that the total winding and handling time is 60 minutes.

The fabric is then washed with hot water as set forth in Example I. The textile fabric is dried in the usual way and the desired linen-like finish is obtained by further mechanical manipulation, such as by calendering.

EXAMPLE IV A 67% cotton-33% spun rayon bleached fabric having count per inch of 61/61 and a metric yarn number of 27/ 27 is passed through the apparatus shown in the drawings at a speed of 40 meters/min. The fabric is impregnated for 23 seconds with 19 B. sodium hydroxide at a temperature of 6 C. The excess alkali is removed with squeeze rolls and the textile fabric is wound onto the drum at room temperature. After a total winding and handling time of 45 minutes, the fabric is washed with hot water and with cold water until neutral as described in Example I.

The fabric is then unwound from the drum, finished on a padding machine with an aqueous solution of 5 g./l. stearin soap and 3 g./1. glycerine, and subsequently Idried on a tenter frame. The linen effect so obtained can be further improved by calendering.

What is claimed is:

1. A process for preparing linen-like fabric which comprises contacting a cellulosic fabric with a sodium hydroxide solution having a concentration in the range of from about 10 to about 20 B. at a temperature below C. to impregnate the fabric, winding the impregnated fabric circumferentially onto a perforate drum and maintaining the fabric on the drum and subsequently removing the sodium hydroxide solution from the fabric by passing water radially from the interior of the drum through the fabric.

2. The process of claim 1 wherein the impregnation of the fabric is carried out with a sodium hydroxide solution having a concentration of from about 13 to about 18 B. at a temperature of from -5 C. to -10 C.

3. The process of claim 1 wherein the fabric is impregnated with the hydroxide solution for from about to about 30 seconds.

4. The process of claim 1 wherein the fabric is circumferentially wound onto the drum at speeds of from about 20 to about 40\r.p.m.

5. The process of claim 1 wherein the sodium hydroxide solution is removed from the fabric by passing water radially through the wound fabric while rotating the drum at speeds of from about 50 to about 300 r.p.m.

6. The process of claim 1 wherein the fabric is wound and maintained on the drum during a total time from about to about 90 minutes.

References Cited UNITED STATES PATENTS 2,498,416 2/ 1950 Hadle'y 68--150 XR FOREIGN PATENTS 1,052,266 9/1953 France.

368,457 5/ 1963 Switzerland.

LEON D. ROSDOL, Primary Examiner I. D. WELSH, Assistant Examiner 

